Benzoxazole and oxadiazole ultraviolet stabilizers

ABSTRACT

Benzoxazole or oxadiazole type compounds chemically combined with certain hydroxyaryl type compounds give greatly and unexpectedly improved ultraviolet stabilization to polymeric materials at concentrations ranging from about 0.05 to about 5.0 percent by weight, preferably from about 0.1 to about 2.0 percent by weight of the polymer being stabilized. These stabilizers are effective in the presence of other additives commonly employed in polymeric compositions including pigments, colorants, fillers, reinforcing agents and the like. These stabilizers may be incorporated into the polymer melt, dissolved in the polymer dope, or coated on the exterior of the molded article, film or extruded fiber.

United States Patent 1191 Irick, Jr. et al.

[451 Feb. 4, 1975 BENZOXAZOLE AND OXADIAZOLE ULTRAVIOLET STABILIZERS [75] Inventors: Gether Irick, Jr.; Charles A. Kelly,

both of Kingsport; James C. Martin, Johnson City, all of Tenn.

[73] Assignee: Eastman Kodak Company,

Rochester, NY.

[22] Filed: Oct. 16, 1972 21 Appl. No.: 298,040

[56] References Cited UNITED STATES PATENTS l2/l970 Duennenberger et al. 260/307 1/1972 Seino et al. 260/240.9

3,679,669 7/l972 Maeder et al 260/240 D Primary ExaminerG. Thomas Todd [57] ABSTRACT Benzoxazole or oxadiazole type compounds chemically combined with certain hydroxyaryl type compounds give greatly and unexpectedly improved ultraviolet stabilization to polymeric materials at concentrations ranging from about 0.05 to about 5.0 percent by weight, preferably from about 0.1 to about 2.0 percent by weight of the polymer being stabilized. These stabilizers are effective in the presence of other additives commonly employed in polymeric compositions including pigments, colorants, fillers, reinforcing agents and the like. These stabilizers may be incorporated into the polymer melt, dissolved in the polymer dope, or coated on the exterior of the molded article, film or extruded fiber.

6 Claims, No Drawings BENZOXAZOLE AND OXADIAZOLE ULTRAVIOLET STABILIZERS This invention concerns novel, ultraviolet stabilizers which are unusually effective for stabilizing various synthetic polymers.

Ultraviolet stabilizers commonly used to protect such polymers as polyesters, polyamides. polyolefins. ABS plastics, polystyrene, poly-(vinyl chloride) and cellulose esters from the deleterious effects of solar irradiation, typically include the Z-hydroxybenzophenones (typified by l) and the Z-hydroxybenzotriazoles (typi fled by ll).

It will be seen hereinafter that these compounds are not nearly as effective stabilizers as the compounds of the present invention, nor are they retained in the polymeric composition to such a high degree as the present stabilizers, particularly in thin sections such as in powder coatings.

An object therefore of the present invention is to provide more effective and permanent ultraviolet stabilizers for polymeric composition. This and other objects hereinafter appearing have been obtained in accordance with the present invention through the discovery that benzoxazole or oxadiazole type compounds chemically combined with certain hydroxyaryl type compounds give greatly and unexpectedly improved ultraviolet stabilization to polymeric materials at concentrations ranging from about 0.05 to about 5.0 percent by weight, preferably from about O.l to about 2.0 percent by weight of the polymer being stabilized. These stabilizers are effective in the presence of other additives commonly employed in polymeric compositions including pigments, colorants, fillers, reinforcing agents and the like. These stabilizers may be incorporated into the polymer melt, dissolved in the polymer dope, or coated on the exterior of the molded article, film or extruded fiber.

The new stabilizers of this invention consist of segments A and B or A and C wherein segment A is of the structure:

wherein when X is substituted for hydrogen, X is meta or para to the heterocyclic ring and may be the following: C Hs, Cl, Br, lower alkyl and CN, where n -3; segment B is of the structure:

wherein the radical bond is either meta or para to the carbonyl group, A and B being linked through a group selected from 0 it and -O; and segment C is of the structure wherein R is CHa- H-CH2,

H()CH2CHg-, CH or CnH n+l,where n 2-18, A and C being linked through a carbon-carbon bond. The resulting series of compounds is as follows:

A- A-O-B Examples 1 and 5 below employ the following general method for producing compounds of the type A- CH OB: A-CH X H0 -B ACH OB HX X halogen A base is used, in this case potassium carbonate, to accept the HX.

Example 2 employs the following general method for producing compounds of the type A X HOB AEOB HX X halogen A base is used, in this case sodium hydroxide, to accept the HX.

Examples 3 and 4 employ the following general method for synthesizing compounds of the type A-C.

Type A-O-B. may be prepared as follows by the Ullman reaction:

A-X HO-B A-O-B HX X halogen EXAMPLE 1 a-(4-benzoyl-3-hydroxyphenoxy)2-ptolybenzoxazole To a solution of 21.4 g. (0.1 mole) of 2,4-dihydroxybenzophenone and 28.8 g. (0.1 mole) of Z-(a-bromo-p-tolyl) benzoxazole in 300 ml. of 2- butanone, is added 100 g. of potassium carbonate. The mixture is placed in a S-necked reaction flask equipped with a mechanical stirrer and reflux condenser. The mixture is refluxed for 16 hr., cooled to room temperature and combined with 1000 ml. of ice water. The precipitated solid product is collected by filtration and washed with water. The crude product is recrystallized from 2-butanone, giving 33.0 g. of an off-white solid, m.p. l8485C. (80 percent yield). The structure and purity of the product are confirmed by NMR and elemental analysis.

Preparation of the above benzoxazole reactant is as follows: o-aminophenol is reacted with p-toluic acid to yield 2-(p-tolyl)benzoxazole; this intermediate is then brominated with N-bromosuccinimide to obtain 2-(4- bromomethylphenyl-benzoxazole.

EXAMPLE 2 4-Benzoyl-3-hydroxyphenyl-p-(2-benzoxazolyl)benzoate To a solution of2 l .4 g. (0.1 mole) of 2,4-dihydroxybenzophenone in 150 ml. of water, containing 4.0 g. (0.1 mole) of sodium hydroxide, is added dropwise a solution of 25.7 g. (0.1 mole) of 4-(2-benzoxazolyl)- benzoyl chloride in 400 ml. of chloroform. The reaction mixture is stirred vigorously and heated at reflux for 4 hr. after the addition is complete. The mixture is cooled to room temperature, the organic layer is separated, washed with warm water and filtered through filter-cel. The solvent is evaporated on a steam bath giving 39 g. of a light yellow solid (90 percent crude yield). The crude product is recrystallized from toluene (2X) to give 29 g. of an almost white solid, m.p. l91-192C. (68 percent yield). The structure and purity of the product are confirmed by NMR and elemental analysis.

The above benzoxazolyl reactant was prepared as follows: 2-(p-toly1) benzoxazole was oxidized with air over a suitable catalyst bed to yield 4-( 2-benzoxazolyl)- benzoic acid. This acid was converted to the acid chloride by reaction with thionyl chloride.

EXAMPLE 3 OCl-lcs 4-(2-benzoxazolyl)-4-methoxy-2'-hydroxy benzophenone To a stirred solution of 12.8 g. (0.05 mole) of 4-(2-benzoxazolyl)benzoyl chloride in 200 ml. of 1,2-dichloroethane is added, in small increments. 14.8 g. (0.1 1 mole) of anhydrous aluminum chloride at room temperature. The resulting solution is cooled to 10C. and a solution of 6.2 g (0.05 mole) of mmethoxyphenol in 50 ml. of dichloroethane is added dropwise over a period of 10 min. The reaction mixture is stirred at 10C. for 30 min., then allowed to warm to room temperature and stirred at reflux for 1 hr. The reaction mixture is cooled to room temperature and combined with 300 g. cracked ice containing 50 ml. of concentrated hydrochloric acid. The organic layer is separated and washed 2 times with warm water. The organic layer is filtered through filter-eel and the solvent is evaporated on a steam bath leaving a yellow solid residue. The crude solid product is recrystallized from toluene to give 10 g. yellow crystals, m.p. 177-l79C. (61 percent yield). The structure and purity of the product are confirmed by IR, NMR, and elemental analysis.

In examples 4 and 5 below, the oxadiazole reactant was obtained from the mixed hydrazide which was cyclized to yield 2-bipheny1yl-5-(m-tolyl)- 1,3,4-oxadiazole. This intermediate was then airoxidized over a catalyst bed to the carboxylic acid. This was converted to the acid chloride of Example 4 by reaction with thionyl chloride. ln Example 5, the intermediate was brominated with N-bromosuccinimide to yield the bromomethyl reactant.

EXAMPLE 4 p 3-(5-p-Biphenylyl-1,3,4-oxadiazol-2-yl)-2-hydroxy-4- methoxybenzophenone To a stirred solution of 10 g (0.08 mole) m-methoxyphenol in ml. 1,2-dichloroethane, containing 13.3 g (0.1 mole) of anhydrous aluminum chloride is added dropwise a solution of 18 g. (0.05 mole) 2-biphenylyl-5-m(ch1orocarbonyl)phenyl-l,3,4-

oxadiazole in 400 ml. 1,2-dichloroethane at ambient temperature. The resulting solution is heated at boiling for 4 hr., cooled to 40C. and poured into 500 ml. ice

water containing 50 ml. concentrated hydrochloric acid. After standing overnight, the top layer is decanted from the organic layer. The solvent layer is washed several times with water anddried over sodium sulfate.

The solvent is evaporated on the steam bath, giving a light yellow solid. The crude. product in toluene is treated with Darco G-60 (activated carbon) to yield 21 g. (91%) of a white solid, m.p. 197198C. The structure and purity of the product are confirmed by NMR and elemental analysis.

EXAMPLE 4- [m-(S-p-Biphenylyl-l ,3,4-oxadiazol-2- yl)benzyl]oxy -2-hydroxybenzophenone To a solution of 11 g. (0.05 mole) 2,4-dihydroxybenzophenone and g. (0.05 mole) 2-biphenylyl-5-[3-(bromomethyl)phenyl]-l ,3,4-oxadiazole in 300 ml. Z-butanone is added 50 g. anhydrous potassium carbonate. The mixture is placed in a 3-necked reaction flask, equipped with a mechanical stirrer and reflux condenser, and heated at reflux for 8 hr. The reaction mixture is cooled to 40C. and combined with 500 ml. cold water. The product separates as a gum. The liquid is decanted and the crude product in benzene is treated with Darco 6-60 (activated carbon).

The yield is 12.5 g. (49 percent) of an off-white solid, m.p. l77l 79C. The structure and purity of the product are established by NMR and elemental analysis.

OH 0-0 E o o Other specific compounds coming within the present invention are as follows:

Compound of Examples Concentration Z by weight Control (No Stabilizer) o-o =0 g 0 0- -OC12H2s (1.0)

o:o o-o H 0 1 ibl Demonstration of the Superiority of Compound of Example 5 to a Mixture of its Component Parts A dry-blended mixture of 0.5 g. Example 5 compound and 100 g. unstabilized cellulose acetate butyrate (CAB) powder of Table I was extruded into l/l6-in. diam. rod, pelletized and pressed into lO-mil film. Samples of this film were exposed to a 280-700-' Table II Time-to-Embrittlement (I-Ir.)

Table III Effect of Stabilizers on Time-To-Loss of Impact Strength of Poly(tetramethylene terephthalate), I.V. Approximately 1.2 inherent viscosity of polyester determined at 23 C. in /40 parts by weight of phenol/tetrachloroethane at a concentration of 0.5 g./l00 ml.

Time-To-Loss of Stabilizer (phr.) Impact Strength (Hr.)

None Example Compound 2, Table l (0.5) l700 Example Compound I. Table I (0.5) l700 Example Compound 5, Table l (0.5) 1050 Example Compound 4, Table I (0.5) I700 To demonstrate the low volatility of the compounds of this invention relative to existing stabilizers, compositions were prepared consisting of 2 parts stabilizer and 98 parts polymer formulation; the polymer formu- Effect of Stabilizer System on Time-To-Embrittlement and Inherent Viscosity (I.V.) of Cellulose Acetate Butyrate Films I.V. Time-To- At Embrittlement Stabilizer (phr.) Initial Embrittlement (Hr.)

Mixture of 2-hydroxy-4- L39 1. I5 736 methoxybenzophenone (0.25) and 2-(4-phenylphenyl)-5- (3-methylphenyI)-l.3, oxadiazole (0.25) I Compound of Example 5 [.42 L24 84] lation was primarily a mixture comprising per 100 parts of (40 mole percent) isophthalic/(60 mole percent) terephthalic copolyester of 1,4-cyclohexanedimethanol of an IV. of approximately 0.7, 4 parts of cellulose acetate butyrate, l0 parts of dioctyl phthalate, and [5 parts of TiO,. Extruded pellets of the compositions were ground to a fine powder and then coated onto metal panels. The metal panels with the powder coating were then heated in an oven at 425F. for 10 minutes and the stabilizer losses were determined. These data 9 10 (Table IV) clearly show the lower volatility (higher pH permanence) of the new stabilizers to existing types. g (5o OR Table IV. Stabilizer Losses From Cured Panels 7 -0 v 2 (4) During wherein R is CH or Cn'H n l, where n 2-l8; A Stabilizer 425 curing and C being linked through a carbon-carbon bond. YH 2. The compound a-(4-benzoyl-3- I hydroxyphenoxy)2-p-tolylbenzoxazole of the formula o I E approximately 1002 i0 0 N OH EH5 4"\ 4"\ E 4''\ I I 2 O0 0-CH O-4 0- -o 0 0:o ozr o:o oo I O I CHaO -CH=C(COzCHo)2 992 3. The compound 4-benzoyl-3-hydroxyphenyl-p-(2- H benzoxazolyl)-benzoate of the formula f- OH a OC12H25 I fl o o e Oo 0 E \\'/.\O/ 0:0 o:o Example Compound 2 approximately 07 w 4. The compound 4-( 2-benzoxazolyl)-4-methoxy-2 E l C d l i t 1 0A xamp e ompmm approx ma 8 y hydroxy benzophenone of the formula We claim: 0\ HO 1. A composition of matter comprising compounds of I n segments A and B or A and C wherein segment A is of 0 the structure: 1 0 O T O (X) n /N\ t/ \I/ 0 o-o O o O Q o-o O o--o l0 n o (X) n N-N o-o \o-o 0-0 H ll/ o o o o o o o O 0 \Q/ I I v wherein X 15 meta or para to the heterocycllc ring and 5. The compound 3-(5-p-biphenyl-yl-l ,3,4-oxadiazol- X may be the following: 2-yl)-2-hydroxy-4-methoxybenzo henone of the for- P C H5, Cl, Br and lower alkyl, mula where n 0-2; segment B is of the structure:

' f OCH;5 /OI\ /O-. 0:.

wherein the radical bond is either meta or para to the 6 The Com pound 4 [m-(S-p-brphenylyl-l,3,4- carbonyl group A bemg hnked through a group oxadiazol-Z-yl)-benzyl]oxy Q-hydroxybenzophenone Pg ggo UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,864,354 Dated Februarv 4. 1975 Inventor) Gether Irick, Jr. Charles A. Kelly, James C. Martin It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 48, the heading "EXAMPLE 4p" should read EXAMIPLE 4.

Columns 7-8, line 1, the title of Table I should be inserted --Table I. Weathering Data for Stabilizers in l0mil Cellulose Acetate Butyrate (13.1% Acetyl, 36.5% Butyryl) Films Exposed to a Fluorescent Mercury Lam Column 9, line 53, following "lected from" delete "CH O-;"

Signed and Sealed this thirtieth D 21) Of September 19 75 [SEAL] Arrest:

RUTH .C. MASON C. MARSHALL DANN Arresting Ojfmer Commissioner oflalenls and Trademarks 

1. A COMPOSITION OF MATTER COMPRISING COMPOUNDS OF SEGMENTS A AND B OR A AND C WHEREIN SEGMENT A IS OF THE STRUCTURE:
 2. The compound Alpha -(4-benzoyl-3-hydroxyphenoxy)2-p-tolylbenzoxazole of the formula
 3. The compound 4-benzoyl-3-hydroxyphenyl-p-(2-benzoxazolyl)-benzoate of the formula
 4. The compound 4-(2-benzoxazolyl)-4''-methoxy-2''-hydroxy benzophenone of the formula
 5. The compound 3-(5-p-biphenylyl-1,3,4-oxadiazol-2-yl)-2''-hydroxy-4''-methoxybenzophenone of the formula
 6. The compound 4((m-(5-p-biphenylyl-1,3,4-oxadiazol-2-yl)-benzyl)oxy)-2-hydroxybenzophenone of the formula 